WASHINGTON (Reuters) -U.S. President Joe Biden on Friday will deliver remarks on the contract negotiations between the United Auto Workers (UAW) and the Detroit Three automakers, the White House said, within hours of the union launching strikes at three factories.

The White House did not specify a time for his remarks. The UAW strike at three factories owned by General Motors, Ford and Chrysler-owner Stellantis on Friday, kicked off the most ambitious U.S. industrial labor action in decades.

Biden, who predicted over the Labor Day weekend the union will not strike, spoke to union and automaker leaders on Thursday. On Wednesday, a White House economic adviser said the president wanted both sides to work around the clock to avoid a strike.

The Biden administration is also discussing emergency aid to protect smaller firms that supply U.S. auto manufacturers, a source with knowledge of the matter said on Thursday.

During a summer of labor unrest, Biden has touted his pro-labor policies by speaking out for unions, while his administration behind the scenes tries to smooth the way for deals with employers to avoid costly walkouts, union leaders and administration officials said.

But in a reminder of how hard it is to appease energized workers while tamping down on price hikes that cause inflation, Biden and auto workers' union UAW - the only major union not to endorse his 2024 presidential run - are not on the same page.

Labor unions like the UAW - which represents 146,000 workers are key to Biden's game plan for winning reelection in 2024. He needs their support to win key states like Pennsylvania and Michigan again, which stand to bear the brunt of any major strikes against carmakers.

Biden, 80, is tying his 2024 re-election bid to the health of the economy, highlighting job growth, rising wages and fading recession fears and a prolonged strike could threaten that.

(Reporting by Nandita Bose, Jarret Renshaw and Susan Heavey; editing by Alison Williams, Jason Neely and Nick Zieminski)